Offset printing was discovered after a production error. The first person to use an offset press to print on paper is an American named Ira Washington Rubel. He came upon offset printing in 1903 while operating a lithographic press, typically used to reproduce artwork through printing plates made of limestone and rubber. He forgot to insert paper between the plates, causing the image to be transferred onto the rubber plate. Realizing his mistake, he made adjustments and redid the process. Rubel later found that the rubber plate left a sharper image than the limestone. He soon decided to create a machine that will use that same printing process.
After Rubel’s discovery, Charles and Albert Harris, brothers who owned the Harris Automatic Press Company, decided to create a press of their own and incorporated Rubel’s design. They created a machine modeled after a rotary letter press. The brother’s invention is the model by which modern offset presses today were patterned after, although slightly altered over time because of the different contemporary variations brought by technology.
Traditional and Modern Offset Printing Process
Offset printing uses the same process as that in lithography. Text and images are transferred onto the paper using a lithography technique based on the repellency between water and oil. This process helps prevent ink smudges.
Computer-to-plate (CTP) is a very useful process in modern printing. Through a desktop publishing application, an image is created and outputted on printing plates. CTP provides quality produced prints with accuracy of getting the desired color from the CMYK-generated computer screen.
Plates used in offset printing are faster and more affordable to produce, making CTP an ideal production process for bulk printing. It also helps in producing high-quality products through precise printing registration and image-to-edge repeatability.
The modern offset press is equipped with metal plates, rubber blankets, offset and plate cylinders, and ink rollers. How does it work? The ink from the ink rollers is transferred to the metal plate then onto the rubber plate. The image on the rubber plate is directly pressed onto the paper. Once the print comes out of the press, it goes through an oven to dry. After it goes through the oven, the paper is pressed by chill rollers to prevent the ink from smudging.
A regular offset press can hold up to 2, 000 pounds of paper. Offset presses can also produce large quantity of prints at great speed. Both these facts make offset printing a viable solution for high-quantity printing.
a. Perfecting Press.
This type of printer can print on both sides. Perfecting press is ideal for producing prints with back-to-back designs like postcards, brochures, menus and other similar materials produced in large quantities.
b. Sheet-fed Offset.
Not all offset presses use rolled papers for printing. Sheet-fed offset presses print one sheet at a time. Feeding papers one by one ensures that all the text and images are positioned proportionally on every page. This is ideal for small- to medium-sized printing jobs.
c. Web Offset.
Unlike a sheet-fed offset, this type of printer uses rolls of paper and produces prints at high speed. Web offset press works best for long-run printing jobs. It can make 10 to 20 thousand impressions, making it ideal for low-cost production.
d. Heatset Web Offset.
A heatset offset press is the ideal machine to use for printing glossy or coated papers. It is a type of web offset that uses inks that are dryer-friendly. The ink stays on the surface of the prints while drying, resulting in glossy prints. It is ideal for producing mid- to high-volume prints like catalogs, inserts and magazines.
e. Coldset Web Offset.
Newspapers are mostly printed through a coldest web offset press. This offset has two types of ink drying methods—one absorbs the ink into the underlying paper and the other uses UV-based inks that “cure” on the paper surface after printing. This printing method can produce a large quantity of printed materials.
Most offset presses have three or more cylinders but blanket-to-blanket printers only have two. Like perfecting printers, this press can print on both sides at the same time. There is no impression cylinder since the rolls serve as impression rolls to each other.
a. Letterset. This ink type is called “dry offset” because no water is involved in the printing process. These are normally used for letterpress printing. The inks are transferred from a printing plate to an offset blanket before being pressed onto the substrate. The absence of water results to an unlimited variety of inks produced when printing on paper.
b. Waterless. These are designed to be used in waterless lithography, an offset printing method that uses silicone compounds to prevent the inks from getting into the non-image areas of your plate. Waterless printing is prone to toning, known as the transfer of inks to a non-image area of the plate, and is caused by the rise of the ink’s temperature. Therefore, waterless inks help minimize toning as these are resistant to the temperature changes undergone by the inks during the printing process.
c. Ink/water balance. It is very important for the ink and water to be balanced and proportioned to each other during offset printing. If the ink and water aren’t mixed properly, the ink may not dry on the substrate, making the faultily printed product to be unfit for delivery.
My HP Laserjet adventure
I own a 5-year-old HP laserjet 1020 monochrome printer
that uses 12A black toner cartridges
yesterday, I was printing on Avery shipping labels
what I do is peel one label off the sheet and stick it in precise
position on another used sheet in the same spot where another label used to be
these are 4x2 labels: I do this using homemade label templates
I made using MS Word with its custom margins and insert shapes features
I do this because I don't print a sheet of labels wholesale,